Axial cooling of a rotor

Abstract

A rotating electric machine ( 1 ) having a stator ( 2 ) provided with windings and a rotor ( 4 ) provided with field windings and with salient poles ( 10 ) forming pole gaps ( 9 ) between the pole shoes ( 12 ) of the poles ( 10 ), which rotor ( 4 ) is arranged to be cooled by air flowing axially through the pole gaps ( 9 ) of the rotor ( 4 ), wherein each pole gap ( 9 ) between the pole shoes ( 12 ) is covered by at least one covering member ( 14 ) and that the air gap ( 15 ) is equipped with a sealing ring ( 16 ) to limit axial air flow.

What is claimed is:  
     
       1. An air flow control for reducing ventilation losses in a rotating electric machine formed with a stator having a central opening and a rotor mounted for rotation within the central opening and having end portions, said rotor and stator having an air gap therebetween, the stator includes stator windings, and the rotor includes field windings, and salient poles in the air gap facing the stator and pole shoes disposed in spaced relation and having adjacent lateral margins forming pole gaps between the pole shoes and a cover member disposed between the pole shoes extending between the adjacent lateral margins for covering each of the pole gaps between the pole shoes forming an axial channel having openings at the ends for carrying a flow of cooling air therethrough and sealing means in the air gap for limiting the flow of air in the air gap. 
     
     
       2. The machine as claimed in  claim 1 , wherein the sealing means comprises at least one fixed sealing ring arranged around the rotor in the air gap between the stator and the rotor. 
     
     
       3. The machine as claimed in  claim 2 , wherein the machine has an air-inlet side and the sealing ring is located on the air-inlet side of the machine. 
     
     
       4. The machine as claimed in  claim 1 , wherein the sealing means comprises at least one internally fixed sealing ring arranged around the stator in the air gap between the stator and the rotor. 
     
     
       5. The machine as claimed in  claim 1 , further including a fan secured to the rotor for producing the flow of air. 
     
     
       6. The machine as claimed in  claim 1 , wherein the cover member has an opening near an axial center of the rotor so that the air can be deflected from an axial direction to a radial direction out through an air duct in the stator. 
     
     
       7. The machine according to  claim 1 , wherein the stator winding comprises a high-voltage cable. 
     
     
       8. The machine according to  claim 1 , wherein the sealing means comprises an air choker to limit the flow of air through the pole gaps.